: Door interlock or the car is quite a rare purchase in the house, because many have no idea what it is or just ignore with regard to its high cost. But if a person thinks about high-quality tailoring and in particular about the tailoring of knitted products, the question of need and price departs on the second plan, because without resposibilty and can be no question about the quality of the lines.
The seams, which makes interlock machine, characterized by high strength and elasticity, and they don't bloom when you damage one of the threads. Therefore, the main application coverstitch seams is in the knit, because the material stretches very much and is problematic for universal sewing machines.
If you compare the principle of construction of lines on the machines lockstitch (universal)
and machines chain stitch
you will notice that the Shuttle stitch both strands equally tensioned and with a bit of stretching can burst, and when using chain stitch lower thread performs the role of shock absorber that allows the stitching to stretch along with a stitched material that makes it indispensable for stretching materials
So: door machine is a lifesaver for people engaged in the tailoring of knitted products.